1. Field of the Invention
This invention relates generally to computer systems, and more particularly to systems, methods, and associated apparatus for computer data migration.
2. Description of the Background Art
Online data migration is the process of transferring data from an old storage system to another while data stored in the old storage system remain accessible. Online data migration has become popular with computer users because it allows for storage system replacements with minimum impact on services. Online data migration, in general, is known in the art; e.g., see the paper “CARE Software Solutions, Hitachi On-line Data Migration”, available from Hitachi Data Systems of Santa Clara, Calif., incorporated herein by reference in its entirety.
“Remote copy” is a mirroring technology that involves the copying of data from a local site to a remote site for back-up purposes. Typically, remote copy is done in real-time to provide continuous data protection, and thereby minimize data loss in the event of a disaster such as a storage system crash or unscheduled facility shutdown (e.g., due to fire, earthquake, power loss, etc.). Remote copy software and associated apparatus have been develop for backing-up the storage systems of a local mainframe computer using remote storage systems.
Computer users who have already implemented remote copy face a dilemma when replacing their storage systems during an online data migration. On the one hand, these users typically have a need to upgrade their old storage systems in order to take advantage of the faster speed and higher capacity of newer storage systems. On the other hand, they cannot afford to disrupt their existing remote copy functions, and risk the possibility of data loss, during the online data migration process. Because currently available techniques for performing online data migration require that the remote copy function be stopped for long periods of time and/or reconfigured after the migration (which also takes a long time because the remote copy has to start over from an initial copy), most users do not have a choice but to risk data loss during the migration process.
From the foregoing, a technique for performing online data migration with minimum impact on remote copy is highly desirable.